sentry key light comes on after driving?

my sentry key light will come on after a few minutes of driving, the jeep will continue to run fine, this is a intermittent problem because sometimes it never comes on while driving and sometimes the jeep wont start because the light starts to flash as soon as I put the key in the ignition and I have to hit the steering column then it will works fine. I have tried new keys and the same thing...what's going on? btw this is a 2000 Grand Cherokee
thanks Jeff